Vacuum out of control

SILO

MEMBER

1 POST

2004 CHEVROLET IMPALA

V8

FWD

197,000 MILES

Have a 2004 chevy impala 2.8l. Check engine light been on for months. Now getting what appears to be high vacuum condition which is causing several issues. Loud noise at times and some missing. Started after replacing PCV valve. Now tried 3 different PCV valves. And MAP sensor above it. Went to dealer and got all new parts. Any ideas.